His wholesale attack on the author of the Narnia books, which have been among the most beloved stories in children's literature for 50 years, came at the Guardian Hay festival which reaches the third of its nine days today.

Pullman, creator of the His Dark Materials trilogy, is one of a range of star speakers and performers who have so far included Mo Mowlam, the archbishop of Wales, Rowan Williams, reggae singer Linton Kwesi Johnson, Chris Stewart, Michael Frayn, Joe Klein, Harold Evans, and comedian Bill Bailey.

Pullman, attacked by a rightwing columnist as "the most dangerous author in Britain" and "semi-satanic", is celebrated for a trilogy which deliberately takes an opposite line to CS Lewis's Christian tales. In Pullman's world, the universe is ruled by a senile, viciously sadistic deity who has to be deposed in battle so that its inhabitants can join with angels in creating a "republic of heaven".

His impassioned discussion of imagination, spirituality and the poverty of modern secularism chimed with the themes of a 65-minute lecture given to one of the festival's biggest audiences by the archbishop.

In reply to a question, Pull man told an audience made up largely of children and young people that he had first read the Narnia books when he was a teacher. He added: "I realised that what he was up to was propaganda in the cause of the religion he believed in.

"It is monumentally disparaging of girls and women. It is blatantly racist. One girl was sent to hell because she was getting interested in clothes and boys."

Pullman was kinder to the Harry Potter stories, the only children's books outselling his own. He said they were great fun, vividly told.

Asked about his concept of a republic of heaven, Pullman said: "When it was possible to have a belief about God and heaven, it represented something we all desired. It had a profound meaning in human life.

"But when it no longer became possible to believe, a lot of people felt despair. What was the meaning of life? It seems that our nature is so formed that we need a feeling of connectedness with the universe. If there is no longer a king, or a kingdom of heaven, it will have to be a republic in which we are free citizens. We ourselves as citizens have to build the republic of heaven."

The Labour ex-cabinet minister, Mo Mowlam, drew a sell-out audience of 1,100, the biggest so far, for an interview session with the Today programme presenter James Naughtie. To applause, she fended off efforts to cajole her into discussing tensions between the prime minister Tony Blair and the chancellor, Gordon Brown. "If I breathe in the wrong direction in relation to either of them, it's a story."

But she was more forthright when asked about Mr Blair's long-term strategy. "I am not sure that the long-term strategy is any longer viable," she said. "I assume it was to move the [Labour] party to the centre, form a coalition and get rid of extremes. This strategy is no longer workable because he has not formed a coalition." · The Guardian Hay festival 2002 runs from May 31 to June 9. For full programme details and tickets please visit www.hayfestival.co.uk or call 01497 821217